// Copyright (c) 2017 Intel Corporation
//
// SPDX-License-Identifier: Apache-2.0
//

package main

import (
	"bufio"
	"context"
	"fmt"
	"net"
	"os"
	"path/filepath"
	"strings"
	"syscall"

	"github.com/kata-containers/runtime/pkg/katautils"
	vc "github.com/kata-containers/runtime/virtcontainers"
	"github.com/opencontainers/runc/libcontainer/utils"
)

// Contants related to cgroup memory directory
const (
	// Filesystem type corresponding to CGROUP_SUPER_MAGIC as listed
	// here: http://man7.org/linux/man-pages/man2/statfs.2.html
	cgroupFsType = 0x27e0eb
)

var cgroupsDirPath string

var procMountInfo = "/proc/self/mountinfo"

// getContainerInfo returns the container status and its sandbox ID.
func getContainerInfo(ctx context.Context, containerID string) (vc.ContainerStatus, string, error) {
	// container ID MUST be provided.
	if containerID == "" {
		return vc.ContainerStatus{}, "", fmt.Errorf("Missing container ID")
	}

	sandboxID, err := katautils.FetchContainerIDMapping(containerID)
	if err != nil {
		return vc.ContainerStatus{}, "", err
	}
	if sandboxID == "" {
		// Not finding a container should not trigger an error as
		// getContainerInfo is used for checking the existence and
		// the absence of a container ID.
		return vc.ContainerStatus{}, "", nil
	}

	ctrStatus, err := vci.StatusContainer(ctx, sandboxID, containerID)
	if err != nil {
		return vc.ContainerStatus{}, "", err
	}

	return ctrStatus, sandboxID, nil
}

func getExistingContainerInfo(ctx context.Context, containerID string) (vc.ContainerStatus, string, error) {
	cStatus, sandboxID, err := getContainerInfo(ctx, containerID)
	if err != nil {
		return vc.ContainerStatus{}, "", err
	}

	// container ID MUST exist.
	if cStatus.ID == "" {
		return vc.ContainerStatus{}, "", fmt.Errorf("Container ID (%v) does not exist", containerID)
	}

	return cStatus, sandboxID, nil
}

func validCreateParams(ctx context.Context, containerID, bundlePath string) (string, error) {
	// container ID MUST be provided.
	if containerID == "" {
		return "", fmt.Errorf("Missing container ID")
	}

	// container ID MUST be unique.
	cStatus, _, err := getContainerInfo(ctx, containerID)
	if err != nil {
		return "", err
	}

	if cStatus.ID != "" {
		return "", fmt.Errorf("ID already in use, unique ID should be provided")
	}

	// bundle path MUST be provided.
	if bundlePath == "" {
		return "", fmt.Errorf("Missing bundle path")
	}

	// bundle path MUST be valid.
	fileInfo, err := os.Stat(bundlePath)
	if err != nil {
		return "", fmt.Errorf("Invalid bundle path '%s': %s", bundlePath, err)
	}
	if !fileInfo.IsDir() {
		return "", fmt.Errorf("Invalid bundle path '%s', it should be a directory", bundlePath)
	}

	resolved, err := katautils.ResolvePath(bundlePath)
	if err != nil {
		return "", err
	}

	return resolved, nil
}

func isCgroupMounted(cgroupPath string) bool {
	var statFs syscall.Statfs_t

	if err := syscall.Statfs(cgroupPath, &statFs); err != nil {
		return false
	}

	if statFs.Type != archConvertStatFs(cgroupFsType) {
		return false
	}

	return true
}

func setupConsole(consolePath, consoleSockPath string) (string, error) {
	if consolePath != "" {
		return consolePath, nil
	}

	if consoleSockPath == "" {
		return "", nil
	}

	console, err := newConsole()
	if err != nil {
		return "", err
	}
	defer console.master.Close()

	// Open the socket path provided by the caller
	conn, err := net.Dial("unix", consoleSockPath)
	if err != nil {
		return "", err
	}

	uConn, ok := conn.(*net.UnixConn)
	if !ok {
		return "", fmt.Errorf("casting to *net.UnixConn failed")
	}

	socket, err := uConn.File()
	if err != nil {
		return "", err
	}

	// Send the parent fd through the provided socket
	if err := utils.SendFd(socket, console.master.Name(), console.master.Fd()); err != nil {
		return "", err
	}

	return console.slavePath, nil
}

func noNeedForOutput(detach bool, tty bool) bool {
	if !detach {
		return false
	}

	if !tty {
		return false
	}

	return true
}

func getCgroupsDirPath(mountInfoFile string) (string, error) {
	if cgroupsDirPath != "" {
		return cgroupsDirPath, nil
	}

	f, err := os.Open(mountInfoFile)
	if err != nil {
		return "", err
	}
	defer f.Close()

	var cgroupRootPath string
	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
		text := scanner.Text()
		index := strings.Index(text, " - ")
		if index < 0 {
			continue
		}
		fields := strings.Split(text, " ")
		postSeparatorFields := strings.Fields(text[index+3:])
		numPostFields := len(postSeparatorFields)

		if len(fields) < 5 || postSeparatorFields[0] != "cgroup" || numPostFields < 3 {
			continue
		}

		cgroupRootPath = filepath.Dir(fields[4])
		break
	}

	if _, err = os.Stat(cgroupRootPath); err != nil {
		return "", err
	}

	return cgroupRootPath, nil
}